Road safety marker assembly

ABSTRACT

A road safety marker assembly having a road safety marker and a drive wheel supporting at least a portion of the road safety marker above a road surface to permit movement of the road safety marker assembly relative to the road surface. A motor is drivingly connected to the drive wheel for driving the drive wheel to self-propel the assembly relative to the road surface. In one embodiment, the road safety marker assembly includes a receiver for receiving a control signal. The motor is electrically connected to the receiver and is responsive to the signal to drive rotation of the drive wheel to move the assembly relative to the road surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 60/284,948, filed Apr. 19, 2001, which is herein incorporated by reference in its entirety for all purposes.

BACKGROUND OF THE INVENTION

[0002] This invention relates generally to a road safety marker, such as a sign, barricade, cone, barrel, lighting device or the like, and more particularly to a road safety marker assembly capable of automated, self-propelled movement of a road safety marker over a road surface.

[0003] Proper vehicle traffic control is highly instrumental in the safety of highway construction and maintenance workers as well as motorists passing through work zones. Road safety markers, which are generally highly visible markers such as signs, barricades, cones, barrels, lighting devices or other marking structures, are typically used to alert motorists of work zones, road hazards or other hazardous conditions and to direct traffic around or through such conditions. One conventional type of road safety marker is a construction barrel, which is typically an orange colored barrel constructed of rubber or plastic and often used by road construction crews to delineate areas in which road work is being conducted and to increase safety for road construction workers. The lightweight, flexible construction of the barrel also reduces the risk of damage to vehicles that inadvertently impact the barrel.

[0004] Accidents often occur as a result of improper work zone design, work zone housekeeping and driver negligence. Work zone housekeeping, which involves tasks such as the deployment and retrieval of road safety markers as well as the covering, uncovering and/or repositioning of markers as the work zone progresses along a stretch of road, can be time consuming and subject to various risks of injury. Substantial worker time and effort is required to properly deploy and retrieve road safety markers, particularly where the markers must be deployed and retrieved at the beginning and end of each workday. Covering the markers instead of retrieving them is also time consuming. However, leaving the markers in open view at all times can add to unsafe conditions. Manual deployment and retrieval of the road safety markers also places the worker in close proximity to passing motorists, exposing the worker to the risk of serious injury.

[0005] U.S. Pat. No. 5,722,788 discloses a traffic delineator comprised of a barrel having wheels fixed to one side of the bottom of the barrel to permit rolling of the barrel and a handle formed at the top of the barrel for grasping while leaning the barrel back onto the wheels to move the barrel. While repositioning of such a barrel is less burdensome on the worker, the repositioning must be done manually, thereby still placing the worker in close proximity to passing motorists. Deployment and retrieval of such barrels must also still be conducted manually.

SUMMARY OF THE INVENTION

[0006] Among the several objects and features of the present invention may be noted the provision of a road safety marker assembly that is easily moved relative to a road surface; the provision of such a road safety marker assembly that is self-propelled; the provision of such a road safety marker assembly that may be controlled from a location remote from the assembly; the provision of such a road safety marker assembly which may be deployed and retrieved from a location remote from a desired deployment location; the provision of such a road safety marker assembly which reduces the risk of injury to construction workers; the provision of a road safety marker system in which multiple road safety marker assemblies are used in combination to form a work zone; and the provision of a method of setting up a road construction work zone in which at least one road safety marker assembly is deployed from the work zone and then moved under its own power to the work zone.

[0007] In accordance with one aspect of the present invention, a road safety marker assembly generally comprises a road safety marker and a drive wheel supporting at least a portion of the road safety marker above a road surface to permit movement of the road safety marker assembly relative to the road surface. A motor is drivingly connected to the drive wheel for driving the drive wheel to self-propel the assembly relative to the road surface.

[0008] In another aspect, the road safety marker assembly comprises a road safety marker and a base adapted for receiving the road safety marker thereon. The base has at least three wheels mounted thereon for moving the assembly relative to the road surface. The at least three wheels are arranged relative to each other such that the base supports the entire road safety marker above the road surface.

[0009] In accordance with one aspect of a road safety marker system of the present invention, the road safety marker system generally comprises a plurality of road safety marker assemblies. Each road safety marker assembly comprises a road safety marker and a base supporting the road safety marker. The base has a drive wheel supporting the road safety marker assembly to permit movement of the assembly relative to a road surface. A motor is drivingly connected to the drive wheel for driving the wheel to self-propel the road safety marker assembly relative to said road surface. A control circuit selectively controls movement of the road safety marker assembly relative to the road surface. The motor is responsive to the control circuit to move the assembly relative to the road surface.

[0010] In accordance with one aspect of a method of the present invention for establishing a road construction work zone generally comprises deploying at least one road safety marker assembly on a road surface at a first location remote from a desired location of the at least one road safety marker assembly. The desired location of the at least one road safety marker assembly corresponds to the road safety construction work zone. The road safety marker assembly comprises a road safety marker, a drive wheel supporting at least a portion of the road safety marker above the road surface to permit movement of the road safety marker assembly relative to the road surface, and a motor drivingly connected to the drive wheel for driving the drive wheel to self-propel the assembly relative to the road surface. The at least one road safety marker assembly is instructed to move under its own power to the desired location of the at least one road safety marker assembly remote from the first location of the at least one road safety marker assembly.

[0011] Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a side elevation of a road safety marker assembly according to one embodiment of the present invention;

[0013]FIG. 2 is a side elevation of the road safety marker assembly of FIG. 1 with a road safety marker removed to show a base of the assembly;

[0014]FIG. 3 is a top plan view of the base of the assembly;

[0015]FIG. 4 is a top plan view similar to FIG. 3 with an electronics table of the base omitted to reveal additional construction of the base;

[0016]FIG. 5 is a bottom plan view of the road safety marker assembly of FIG. 1;

[0017]FIG. 6 is an exploded perspective of a portion of the base;

[0018]FIG. 7 is a block diagram illustrating a control circuit of the road safety mark assembly of FIG. 1 according to a preferred embodiment of the invention;

[0019]FIG. 8 is a schematic diagram of an input circuit of the control circuit of FIG. 7;

[0020]FIG. 9 is a schematic diagram of a motion control circuit of the control circuit of FIG. 7;

[0021]FIG. 10 is a schematic diagram of a decoder circuit of the control circuit of FIG. 7;

[0022]FIG. 11 is a schematic diagram of a motor driver circuit of the control circuit of FIG. 7;

[0023]FIG. 12 is a block diagram of a road safety marker system according t o one embodiment of the invention; and

[0024]FIG. 13 is a block diagram of a road safety marker system according to another embodiment of the present invention.

[0025] Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0026] Referring now to the drawings and in particular to FIG. 1a road safety marker assembly of the present invention is indicated in its entirety by the reference numeral 21. The assembly 21 comprises a road safety marker, generally indicated at 23, and a base, generally indicated at 25, supporting the road safety marker above a road surface for self-propelling the assembly relative thereto.

[0027] The road safety marker 23 is shown and described herein as a conventional construction barrel constructed of a flexible plastic or rubber material and standing approximately 36 inches in height. The barrel 23 is orange colored and may have reflective stripes (not shown) painted or adhered to its outer surface to increase visibility of the barrel to motorists at night. The barrel 23 has a tubular side wall 27, a closed upper end 29 and an open lower end 31 together defining a hollow interior (not shown) of the barrel. A handle 33 is formed integrally with the closed upper end 29 of the barrel for grasping when lifting or moving the barrel. The lower end 31 of the barrel 23 is generally circular, and is more particularly D-shaped, with a central opening (not shown) and a flat 34 formed along a segment of the rear (e.g., the left side as shown in FIG. 1) of the barrel. The diameter of the barrel side wall 27 is generally stepped inward from the lower end 31 to the upper end 29 to increase the strength of the barrel 23 and to allow nesting of several barrels. It is understood that the road safety marker 23 of the assembly 21 of the present invention may be other than a barrel, such as a sign, traffic cone, barricade, portable lighting device or other marking structure without departing from the scope of this invention.

[0028] With reference to FIGS. 2 and 3, the base 25 of the assembly 21 is generally circular and is sized radially (e.g., laterally) for seating the lower end 31 of the safety marker 23 on the base so that the base supports the entire safety marker above the road surface. The base 25 may also have a flat (not shown) along its peripheral edge at the rear of the base so that the shape of the base is D-shaped to correspond generally to the footprint of the road safety marker 23. A generally annular positioning member 35 is formed on the upper surface of the base 25 inward of its peripheral edge, extending substantially circumferentially about the base with the exception of a small open segment 37 at the rear (e.g., the right end in FIG. 3) of the base. The positioning member 35 and the upper surface of the base 25 between the positioning member and the peripheral edge of the base together define a shoulder 39 for positioning the safety marker 23 on the base.

[0029] The outer diameter of the positioning member 35 is slightly less than the diameter of the central opening of the lower end 29 of the safety marker 23 so that the positioning member properly locates the safety marker on the shoulder 39 with the positioning member and the lower end of the safety marker in closely spaced relationship with each other to inhibit sliding movement of the safety marker relative to the base. The upper surface of the base 25 and the hollow interior of the road safety marker 23 together define an enclosure of the road safety marker assembly 21 for housing various operating components of the assembly as described later herein. As an example, the base 25 of the illustrated embodiment is constructed of aluminum having a thickness of about 0.25 inches and a diameter of about 24 inches. The positioning member 35 is set radially inward from the peripheral edge of the base 25 about 2 inches and is sized approximately 0.75 inches in width and 0.75 inches in height. The road safety marker 23 of the illustrated embodiment is thus free from any fixed or releasable connection to the base 25 so that the marker can be easily lifted off of the base for storage and transport of the assembly 21 or knocked off of the base in the event the assembly is impacted by a vehicle. However, it is understood that the road safety marker 23 may alternatively be releasably connected to the base 25, or it may be fixed to the base, without departing from the scope of this invention.

[0030] The road safety marker assembly 21 is further supported above the road surface in a generally horizontal orientation by a pair of drive wheels 41 and a caster 43. The drive wheels 41 and caster 43 are mounted on the base 25 with the drive wheels in laterally spaced relationship with each other and the caster disposed rearward of and generally centrally between the drive wheels whereby the drive wheels and caster together form a generally triangular formation for supporting the assembly 21. The drive wheels 41 and caster 43 are spaced relative to each other so that the center of gravity of the road safety marker assembly 21 is positioned within the triangular formation defined by the drive wheels and caster. In this manner, the weight of the assembly 21 is stably supported by the drive wheels 41 and caster 43 and is generally evenly distributed among the drive wheels and caster. In stating that the center of gravity of the road safety marker assembly 21 is positioned within the triangular formation defined by the drive wheels 41 and caster 43, it is understood that the center of gravity may be located vertically above or below the triangular formation, as long as the horizontal location of the center of gravity falls within the triangular formation.

[0031] As an example, the combined weight of the base 25 and the road safety marker 23 of the assembly 21 shown in FIG. 1 is about 50 lbs. The lateral spacing between the drive wheels 41 is approximately 13 inches and the spacing between each drive wheel and the caster 43 is approximately 12 inches. The center of gravity of the assembly 21 is located approximately 3.5 inches above the base 25 of the assembly and falls within the triangular formation defined by the drive wheels 41 and the caster 43. As a result, the road safety marker assembly 21 of the illustrated embodiment is capable of withstanding wind blowing at up to 55 mph without becoming unstable and tipping over.

[0032] As shown in FIG. 4, the drive wheels 41 are mounted on the base 25 radially inward of the positioning member 35 so that the drive wheels are disposed primarily within the enclosure defined by the base and the hollow interior of the road safety marker 23. Each drive wheel 41 extends down through a respective longitudinally extending slot 47 formed in the base 25 inward of the positioning member 35 to a location below the base (FIGS. 1 and 2). The drive wheels 41 each include a hub 49 constructed of plastic, and a rubber tire 51 mounted on the hub. Each hub 49 has a central opening 53 (FIG. 6) for receiving an axle 55 therethrough to mount a respective one of the drive wheels 41 for conjoint rotation on the axle. In other words, there are two independent axles 55, one corresponding to each drive wheel 41, so that the drive wheels are rotatable independently of each other. However, the axles 55 are positioned relative to each other so that the axles share a common rotation axis.

[0033] Each axle 55 is secured to the base 25 by opposed, generally L-shaped mounting brackets 57 positioned on laterally opposite sides of the respective drive wheel 41. Each mounting bracket 57 has a bearing 59 secured therein and sized for receiving the axle 55 therethrough to permit rotation of the axle relative to the mounting brackets. The axles 55 are supported by the mounting brackets 57 and bearings 59 at a predetermined height above the base 25 so that only the tire 51 and small portion of the hub 49 of each drive wheel 41 extend down through the respective slot 47 in the base for supporting the road safety marker above the road surface.

[0034] As an example, the drive wheels 41 of the illustrated embodiment have a diameter of about 7.5 inches. The opposed L-shaped mounting brackets 57 are each constructed of aluminum having a thickness of about 0.125 inches, a width of about 2 inches, a height of about 2 inches and a depth of about 1.5 inches. The bearings 59 are conventional steel, double shielded, lubricated, sealed and flanged bearings having a dynamic load rating of about 575 lbs and a static load rating of about 305 lbs. The bearings 59 each have an outer diameter of about 0.875 inches and a bore diameter through which the axle 55 extends of about 0.375 inches. The bearings 59 secured in the mounting brackets 57 support the axles 55 approximately 1.25 inches above the base 25. Since the base 25 has a thickness of about 0.25 inches, a maximum radial extent of approximately 2.25 inches of each drive wheel 41 extends down through the respective slot 47 in the base to support the base of the road safety marker assembly 21 approximately 2.25 inches above the road surface. However, it us understood that the axles 55 may be disposed higher or lower relative to the base to vary the height of the assembly above the road surface. It is also contemplated that the axles 55 may be disposed below the base 25 without departing from the scope of this invention.

[0035] The axles 55 of the illustrated embodiment are each about 1.875 inches long and include a central portion 61 having a diameter of approximately 0.5 inches for passage through the central bore 53 of the hub 49. Outer ends 63 of each axle have a reduced diameter (e.g., about 0.375 inches in the illustrated embodiment) for extending through the bearings 39. A locking pin (not shown) extends generally diametrically through the hub 49 and the central portion 61 of each axle 55 to drivingly connect the drive wheel 41 to the axle whereby rotation of the axle drives rotation of the drive wheel. The locking pin, the drive wheel 41 and the axle 55 are preferably bonded together, such as by epoxy. However, it is understood that the axle 55 may be drivingly connected to the drive wheel 41 by methods other than bonding without departing from the scope of this invention.

[0036] The base 25 also has a generally circular opening 65 centrally located between the slots 47 radially inward of the open segment 37 of the positioning member 35 at the rear of the base. A riser 67 is mounted on the base 25 to extend over the opening 65 for supporting a battery unit 69 of the assembly 21, the purposes of which will become apparent. The caster 43 has a mounting assembly 71 secured to the bottom of the riser 67 and extending down through the opening 65. The height of the riser 67 and the length of the caster mounting assembly 71 are sized relative to each other so that the caster 43 is positioned below the base 25 a distance substantially the same as the radial extent of the drive wheels 41 below the base whereby the drive wheels and the caster together support the base above the road surface in a generally horizontal orientation relative to the road surface.

[0037] It is understood, however, that the drive wheels 41 and caster 43 may support the base 25 in a tilted (e.g., non-horizontal) orientation relative to the road surface without departing from the scope of this invention. It is also contemplated that any number of wheels and/or casters may be used, with only one wheel being a drive wheel 41 or more than one of the wheels being a drive wheel, without departing from the scope of this invention. For example, the base 25 may be supported by a single drive wheel and a pair of casters. Also, only one wheel, such as one drive wheel 41, may be mounted on the base and/or the caster 43 may be omitted, such that only a portion of the road safety marker assembly 21 is supported above the road surface, and remain within the scope of this invention.

[0038] Each drive wheel 41 is independently driven by a respective motor 73 and drive assembly, indicated generally at 75, drivingly connecting the motor to the drive wheel. The motor 73 and drive assembly 75 are further described herein with particular reference to FIG. 6, which illustrates the left drive wheel 41, motor and drive assembly, it being understood that the right drive wheel, motor and drive assembly are substantially identical thereto. The motor 73 is secured to the base 25 by a generally L-shaped mounting bracket 79 and has a drive shaft 81 extending outward therefrom through an opening 83 in the mounting bracket. The mounting bracket 79 of the illustrated embodiment is constructed of aluminum having a thickness of about 0.125 inches and is about 2 inches wide, 2.5 inches high and 2.5 inches deep. The motor 73 is an electrically powered motor powered by the battery unit 69.

[0039] The drive assembly 75 comprises a drive gear 85 mounted on the drive shaft 81 of the motor 73 on the side of the mounting bracket 79 opposite the motor for conjoint rotation with the drive shaft. The drive gear 85 of the illustrated embodiment is a twenty-four pitch gear having an outer diameter of about 2.7 inches and a pitch diameter of approximately 2.625 inches. The drive gear 85 is secured to the drive shaft 81 by a set screw (not shown) extending centrally through the drive gear and threaded into an internally threaded bore (not shown) formed longitudinally in the end of the drive shaft. The drive assembly 75 further comprises a wheel gear 87 secured to the inner end of the axle 55 via a similar set screw (not shown) threaded into an internally threaded bore (not shown) in the axle for conjoint rotation with the axle.

[0040] A tubular extension 88 (FIG. 4) of the wheel gear 87, and an annular spacer 89 mounted on the axle 55 between the extension and the bearing 59, longitudinally space the wheel gear 87 from the bearing. The extension 88 and spacer 89 are sized in length so that the wheel gear 87 is generally longitudinally aligned with the drive gear 85 for driving interengagement therewith. As a result, the teeth of the wheel gear 87 are intersticed with the teeth of the drive gear 85 to drivingly connect the gears, thereby drivingly connecting the drive wheel 41 with the motor 73. As an example, the wheel gear 87 of the illustrated embodiment is also a twenty-four pitch gear and has an outer diameter of about 2.08 inches and a pitch diameter of about two inches. Thus, it will be seen that the gear ratio of the drive assembly 75, i.e., the ratio of the pitch diameter of the drive gear 85 to the pitch diameter of the wheel gear 87, is about 1.325.

[0041] With reference back to FIGS. 2 and 3, an electronics table 91 is mounted on the upper surface of the base 25 intermediate the drive wheels 41 for mounting the various electronic components and circuit boards of the safety marker assembly 21 up off of the base, e.g., above the height of the wheels, and within the enclosure defined by the base and the hollow interior of the safety marker 23. For example, the electronics table 91 of the illustrated embodiment is disposed approximately 7.125 inches above the upper surface of the base 25.

[0042]FIG. 7 illustrates a preferred embodiment of an electrical control circuit for controlling operation of the road safety marker assembly 21. The control circuit comprises an input circuit, generally indicated at 696, and a safety marker assembly circuit, generally indicated at 698 carried onboard the assembly. For example, the safety marker assembly circuit 698 of the assembly 21 of FIGS. 1-6 is mounted on the electronics table 91. However, it is understood that the assembly circuit could be mounted on the safety marker 23, such as within the hollow interior of the marker, or the circuit could be mounted on the base 25 other than on the electronics table 91, without departing from the scope of this invention. A remote pointing device, such as a joystick 701, is electrically connected to a component box (not shown) which houses a micro-controller 703, an analog to digital (A/D) converter 704, and a Radio Frequency (RF) transmitter 705. In the alternative, another input device, such as a keyboard, mouse, pen, voice input device, touch input device, etc. may be used to provide the input to micro-controller 703.

[0043] The assembly circuit 698 for the road safety marker assembly 21 comprises a motor control circuit 713 and a motion control circuit 714. More specifically, the motion control circuit 714 has a Radio Frequency (RF) receiver 706, a micro-controller 707, decoder circuits 710, 711, and a microprocessor 712. In a preferred embodiment, the decoder circuits 710, 711 are respectively associated with left and right encoders 708, 709. The encoder 708 generates position signals representative of the rotary position of one of the motors 73, which will be otherwise referred to for purposes of disclosing the assembly circuit 698 as the left motor 723, and the encoder 709 generates position signals representative of the rotary position of the other motor, which will be otherwise referred to further herein as the right motor 724. In turn, decoder circuits 710, 711 decode the position signals for use by the microprocessor 712. The motor control circuit includes left and right shift registers 725, 726 respectively associated with left and right H-Bridges 727, 728. The circuits and micro-controller of the assembly are powered by the battery unit 69, which in the illustrated embodiment of FIG. 2 is a DC 12-volt, rechargeable battery.

[0044] Still referring to FIG. 7, the joystick 701 generates one or more control signals for determining the speed, direction, and braking effect of a particular road safety marker assembly 21 or several such assemblies. For example, joystick 701 provides an analog signal to the A/D converter 704. The digital signal output from the converter 704 serves as an input signal to the micro-controller 703. The micro-controller 703 is, for example, a Basic Stamp II (BS2) computer available from Parallax, Inc. The BS2 has 16 I/O pins plus two synchronous serial pins, holds 500 to 600 instructions, and is capable of executing an average of 4000 instructions per second. In a preferred embodiment, micro-controller 703 executes an algorithm that interprets and converts the digital signal into binary code data. The binary code data consist of one byte, or eight bits, of information. These bits of information are transmitted by RF transmitter 705 to RF receiver 706 mounted onboard the road safety marker assembly 21. The transmitted communication contains 8 bits of information for each of the motors 723, 724. Preferably, the first 2 bits contain the safety marker assembly number and activation status for the left and/or right drive wheels, such as drive wheels 41 of the embodiment of FIGS. 1-6, which will be otherwise referred to further herein for purposes of disclosing the assembly circuit 698 as left drive wheel and right drive wheel corresponding respectively to the left and right motors 723, 724; the second 2 bits contain braking and direction instructions respectively; and the next 4 bits contain speed commands. The information contained in the 8th bit also determines whether a particular assembly 21 will react to a given control signal from joystick 701.

[0045] With reference to FIG. 8, a 9-volt battery 715 powers joystick 701. Joystick 701 provides commands via, for example, a two-directional variable resistor arrangement. In this embodiment, voltage regulator 716 applies a continuous five volts through two variable resistors, or potentiometers (pots) 717 and 718, where resistance varies with joystick 701 motion. Varying resistance with pot 717 effects left and right motion, and varying resistance with pot 718 effects forward and reverse motion. The joystick's trigger switch 719 is used as a brake and is either on or off. The variable resistance of the joystick 701, enabled by pot 717 and pot 718, is in a voltage divider arrangement with resistors 719, 720 and 721. Joystick 701 sends variable voltage output to the A/D converter 704. Further, rotary switch 700 allows for simultaneous or independant control of several road safety marker assemblies 21.

[0046] The A/D converter 704 is, for example, a type LTC1298 converter available from Linear Technology. A/D converter 704 converts an analog signal, i.e., the variable voltage output, into a digital representation of the joystick's orientation. In this embodiment, one pin is the chip select input. A logic low on this input enables the A/D converter 704, and a logic high disables the chip. Converter 704 also has two analog inputs and a ground pin. A digital data input is preferrably connected to a digital data output through a resistor 775. Converter 704 also has a shift clock, which synchronizes the serial data transfer and determines conversion speed, and a power supply and reference voltage connection. The digital representation output by A/D converter 704 is a twelve-bit binary number, for example, which converter 704 sends to micro-controller 703. Micro-controller 703 executes an algorithm using the bit information and outputs the resulting data to the RF transmitter 705.

[0047] The RF transmitter 705 is, for example, a type RFD 433T 433 MHz available from Parallax, Inc. The RF transmitter 705 transmits data via RF communication that is ultimately used to control the left and right motors 723, 724. As shown in FIG. 8 the transmitter 705 is connected to power supply ground and its power supply pin is connected to a regulated +5VDC. A high state, logic 1, on the mode pin insures the module operates in serial mode. Transmitter 705 receives serial data via a data input pin and uses a Serial Flow Control Pin to achieve maximum serial throughput.

[0048] Referring again to FIG. 7, the functional block diagram of the illustrated embodiment shows a remotely generated control signal received by a RF receiver 706 onboard the road safety marker assembly 21, and the subsequent processing of the data contained within that signal. The RF receiver 706 onboard the assembly 21 receives instructions in binary code format from the remotely generated control signal. The binary code contains one byte, or eight bits, of information for each motor 723, 724. Preferably, the first 2 bits contain a particular road safety marker assembly number, and activation status for the left and/or right drive wheels; the second 2 bits contain braking and direction instructions, respectively; and the next 4 bits contain speed commands. Further, the information contained in the 8th bit determines whether a particular assembly 21 will react to a given control signal. This signal can be received by any number of receivers, such as receiver 706, tuned to its frequency and within reception range. Although described in connection with RF control signals, it is to be understood that alternative embodiments of the invention may employ other transmission methods for communicating control signals (e.g., wired media and wireless media such as acoustic, RF, infrared, etc.).

[0049] The RF receiver 706 outputs data to micro-controller 707 onboard the road safety marker assembly 21. In this embodiment, micro-controller 707 is also, for example, a BS2 computer available from Parallax, Inc. Micro-controller 707 outputs data to the microprocessor 712 of the assembly 21, which is for example, a TFX11 microprocessor manufactured by Onset. Through programming code, the microprocessor 712 determines the safety marker assembly number, left and right motor control, braking effect, direction of travel and the speed for a particular assembly 21 from the parallel data output from micro-controller 707.

[0050] Referring now to FIG. 9, the motion control circuit 714 of assembly circuit 698 is shown in the form of a schematic diagram. The battery unit 69 powers the assembly circuitry 698, but voltage regulator 716 regulates the voltage and supplies an input of +5 VDC to the RF receiver 706, micro-controller 707, and microprocessor 712.

[0051] The RF receiver 706 is, for example, a type RFD 433R 433 MHz available from Parallax, Inc. In this embodiment, RF receiver 706 receives an eight-bit RF communication from a remote communication device, such as joystick 701. One pin of the receiver 706 is grounded. Another pin of the receiver 706 is connected to the regulated +5 VDC. A mode select pin is, preferably, connected to +5 VDC so that the RF receiver 706 operates in serial mode. A pin labeled RXD outs serial data to micro-controller 707. Micro-controller 707 is programmed to convert the serial byte instructions from RF receiver 706 into individual bits, such that the data may be transferred in parallel. Based on the output from micro-controller 707 and programming code stored in the microprocessor 712, the microprocessor determines whether a particular road safety marker assembly 21 will react to a RF signal received by the RF receiver 706. Accordingly, several assemblies may receive the same RF signal, but if the information in the 8th bit does not match the code information stored in the microprocessor 712 for a particular assembly 21, that assembly will not react to the signal.

[0052] Referring again to FIG. 7, the functional block diagram of the illustrated embodiment that enables motion control is also shown. The safety marker assembly 21 preferably controls motion by encoding and decoding signals generated by the motors 723, 724 and then processing the decoded signal along with signals generated by the micro-controller 707.

[0053] In FIG. 7, the motion control circuit 714 enables motion control. Left and right encoders 708 and 709 provide signals to left and right decoders 710 and 711, respectively. The encoders 708 and 709 encode the position of the drive wheel using a digital format. The decoders 710 and 711, along with micro-controller 707, output signals to microprocessor 712. Based on these signals, microprocessor 712 executes an algorithm that calculates the current motion for both the left and right drive wheels for generating a motion control signal. Preferably, the motions calculated include braking effect, direction of rotation, and overall rotational speed.

[0054] The following equations, developed as a function of the gear ratio of the drive assembly 75 and the drive wheel 41 size, are preferably used by microprocessor 712 to calculate the current position, orientation and velocity of the safety marker assembly 21.

[0055] Dm/Dw=2.625/2=1.3125=Gear ratio (Gr)

[0056] q_(wheel)=q_(motor)*Gr=q_(motor)*1.3125 (rad)=rotational position of wheel

[0057] X_(wheel)=q_(wheel)*R_(wheel)=[q_(motor)(rad)*1.3125]*0.3125 (ft)=q_(motor)*0.410 (ft)

[0058] w_(wheel)=w_(motor)*Gr=w_(motor)*1.3125 (rad/sec)=rotational velocity of wheel

[0059] V_(wheel)=w_(wheel)*R_(wheel)=[w_(motor)(rad/sec)*1.3125]*0.3125 (ft)=w_(motor)*0.410 (ft/sec)

[0060]FIG. 10 illustrates portions of the motion control circuit 714 in greater detail. Preferably, the same voltage regulator 716, that supplies +5 VDC to RF receiver 706 also supplies a +5 VDC to decoders 710 and 711. Encoders 708 and 709 are integrated respectively with the motors 723, 724 of the drive wheels, and encode the motors' rotational positions to provide an analog output to decoders 710 and 711, respectively.

[0061] The decoders 710 and 711 are, for example type LS7166 counters, which serve as decoders and are available from LSI Computer Systems, Inc. The decoders 710 and 711, convert analog rotational information received from encoders 708, 709 to corresponding digital signals. In this instance each counter circuit provides an 8-line data bus for interfacing the system bus.

[0062] Referring again to FIG. 7, motor control is enabled by translating signal information received from the motion control circuit 714, via microprocessor 712, into power for driving the motors 723, 724. The motor control circuit 713 receives 12 bits of data serially from microprocessor 712 in this embodiment. The 12 bits of data preferably consist of 6 bits for each motor 723, 724. The 6 bits of instructions include one bit for braking, one bit for direction and a 4 bit binary code for controlling motor speed. In addition to serial data, registers 725 and 726 also receive clock and latch signals from microprocessor 712. The serial bit instructions are cyclically converted into parallel format, shifted out of registers 725 and 726, and then input directly into H-bridge chips 727 and 728. The information input into each of the two H-bridge chips 727 and 728 consists of 6 bits. As described above, the 6 bits of instruction determine braking effect, direction, and motor speed. In addition, corresponding pulse width modulated (PWM) signal is also generated from the 6 bit input. The generated PWM signal is then sent in an analog fashion to the motors 723, 724 for driving the motors.

[0063] Referring now to FIG. 11, the motor control circuit 713 is shown in greater detail. Registers 725 and 726 are, for example, 74HC595 shift registers manufactured by Philips Semiconductors. Registers 725 and 726 are powered with a 5-volt input and receive serial data input. Eight pins provide parallel data output to the respective bridge circuit 727 or 728. The H-bridge chips 727 and 728 are, for example, type LMD18245 motor drivers manufactured by National Semiconductor. The H-bridge chips 727 and 728 are configured for generating the PWM signal to be supplied to the motors 723, 724. The current of the PWM signal is determined by a separate current sensing (CS) amplifier, within the H-bridge chip, and is controlled by resistors 733 and 734. The PWM signal allows transistors, also within the H-bridge chip, to be fully “on” or “off” and thus creates an average voltage supply to the motors 723, 724. If more voltage is required, the transistors are “on” longer than if less voltage is required.

[0064] Although H-bridge chips 727 and 728 are powered with the regulated +5 VDC, the battery unit supplies 12 volts for use in generating the PWM signal. Resistors 729 and 731 and capacitors 730 and 732 are connected between the driver and ground, as recommended by the manufacturer, to stabilize the monostable timing pulse. In this instance, each bridge circuit 727, 728 accepts the four bit binary speed input as well as brake logic input and direction logic input. Resistors 733 and 734, capacitor 735 and 736 are also recommended by the manufacturer.

[0065] As described above, the illustrated embodiment utilizes microprocessors for controlling the road safety marker assembly 21. The micro-controller 703 connected to the joystick 701 serves several purposes. For example, it determines the orientation of the joystick 701; performs a series of calculations based on this position as well as the trigger 719 position; and finally sends this information to the RF transmitter 705 within the component box 702. This set of instructions is preferably repeated over and over during operation at a rapid rate. With respect to programming code for micro-controller 703, the micro-controller first initializes the system and prepares to receive the forward/reverse information from A/D converter 704. Based on this information the direction bit is set high or low. Also, a preliminary speed nibble is set based on the joystick 701 position as read by micro-controller 703 through the A/D converter 704. Next, the right/left motion information is obtained by the micro-controller 703 from A/D converter 704 for determining motion of the left or right drive wheel. Micro-controller 703 calculates a secondary speed nibble based on the joystick 701 position. Proceeding to a calculations subroutine, micro-controller 703 determines the speed for the left drive wheel and the speed for right drive wheel and then sets the preliminary speed nibble for one drive wheel and the preliminary speed nibble plus the secondary speed nibble for the other drive wheel. This allows turning of the safety marker assembly 21 to occur.

[0066] The micro-controller 703 finally composes the data to be sent via RF transmitter 705. This is done once for both the left and right drive wheel each time through the loop. In addition to the speed nibble for each drive wheel, micro-controller 703 adds a brake command from the joystick trigger 719, as well as a direction bit and an assembly number bit. These bits are composed in the following order and sent to the RF transmitter 705:

[0067] Assembly Number, L/R, Brake, Direction, Speed 4, Speed 3, Speed 2, Speed 1.

[0068] For example if an operator pushes forward and to the left, the following is transmitted if this is the first assembly and the brake is off:

[0069] 00010011

left drive wheel command of a slow speed

[0070] 01011111

right drive wheel command of a faster speed

[0071] The alternating L/R bit allows independent control of the two drive wheels while confining the instructions to one byte. The RF receiver 706 of the assembly receives this data and then, through a series of operations, the data arrives at registers 725, 726. The registers shift out the data to motor drivers 727 and 728, which power the motors 723, 724 to propel the assembly 21.

[0072] The micro-controller 707 of the road safety marker assembly 21 executes a loop to gather the data sent serially to RF receiver 706 and sends the data to the microprocessor 712 in parallel fashion. Based on the assembly number bit, one of two things will happen. If the assembly number sent does not match the prescribed number set on this program, the brake will be engaged and the speed set to 0000. This feature allows the operator to control several safety marker assemblies 21 independently of one another. Before the program is downloaded to microprocessor 712, the assembly number is entered so it will respond according to the operator's commands. If the assembly number does match, the program goes on to another check.

[0073] After checking the assembly number bit, microprocessor 712 checks the drive wheel bit. Based on the result, microprocessor 712 sends a command to either the left subroutine to update left drive wheel's brake, direction and speed bits, or to the right subroutine to do the same for the right drive wheel's data. In this embodiment, one drive wheel subroutine is updated each cycle through the program. However, data is preferably sent to the motor drivers 727, 728 each cycle. At the speed that such operations are taking place, any time lag caused by the update format is negligible. Microprocessor 712 then assembles the brake, direction, and speed bits for the left and for the right drive wheels and sends the commands serially to the motor driver board 713.

[0074] The present invention preferably executes a local control loop for accurately positioning assembly 21. As described above, assembly 21 preferably receives a commanded position and orientation (or speed and direction) from a central controller or input circuit 696. One embodiment of assembly 21 then uses an inverse Jacobian Cartesian scheme well known to those skilled in the art. This scheme is implemented with a conventional PID control to create left and right torque commands for motors 723, 724, respectively. For example, an error is created in Cartesian space using a desired Cartesian position and a measured position. The error is then transformed into joint space using the inverse Jacobian. The PID control law acts upon the joint space error to create the torque commands.

[0075] Now referring to FIGS. 12 and 13, the road safety marker assembly 21 may be deployed in connection with one or more other road safety marker assemblies as part of a work zone, or road safety marker system. FIG. 12 illustrates one preferred embodiment of a road safety marker system in which each road safety marker assembly can be independently controlled or the assemblies may be linked electronically, and each of the assemblies may have a different type of road safety marker 23, such as the barrel of FIG. 1, a sign, a traffic cone, a barricade or other marking structure, or the assemblies may have road safety markers that are all of the same type.

[0076] For example, one road safety marker assembly 21 functions as a master unit 21 a that moves in response to the control signal received by its receiver 706 from the input circuit 696, or in response to a predetermined pattern stored in the computer readable medium of its microcontroller 707. In either instance, the master assembly 21 a moves as directed and one or more slave units 21 b, 21 c, and/or 21 n follow either at a predetermined position relative to master assembly 21 a or in response to independently generated control signals transmitted by a radio frequency transmitter 732 in master unit assembly 21 a.

[0077] A camera (not shown) or other such monitoring system, mounted on a maintenance vehicle, for example, may be used for monitoring the location of assemblies 21. Preferably, the camera generates an image of the assemblies 21 for processing to determine the locations of each assembly 21 in the group. Highway stripes, for example, may be used as a reference for determining the position of the marker assemblies 21. Commands are then sent to the individual assemblies 21, or to the master assembly 21 a, to instruct movement of the assemblies in a certain way based on the visual feedback provided by the camera. This embodiment permits several assemblies 21 to be controlled together and is particularly beneficial for controlling a moving wedge of markers that follows a road crew. It is to be understood that those skilled in the art are aware of other monitoring systems for determining the position of a particular assembly 21, including, for example, a global positioning system receiver mounted thereon.

[0078]FIG. 13 shows another embodiment of a road safety marker system in which master assembly 21 a transmits a control signal to at least one other assembly 21, such as assembly 21 b. In this embodiment, assembly 21 b includes a transceiver 734 for receiving the RF control signal and for transmitting the same control signal, or a modified control signal, to one or more other assemblies 21, such as assemblies 21 c-n shown in FIG. 13. Although the slave assemblies 21 b-21 n are shown in FIG. 13 as having transceivers 734, it is to be understood that they may includes separate transmitters, such as RF transmitter 732, and separate receivers, such as RF receiver 706.

[0079] In general, master assembly 21 a has greater capabilities than the other assemblies 21 b-21 n. The master assembly 21 a, for example, may include more advanced sensors and computational hardware for making decisions about where the group of marker assemblies 21 should travel and for coordinating their movements. This would allow assemblies 21 to operate in a remote situation, possibly without human intervention, such as for a road closing during severe weather.

[0080] Further to these examples, it is contemplated to distribute the control operation throughout the group of assemblies 21. Under this approach, assemblies 21 communicate with each other to determine the actions of the entire group. This approach is particularly beneficial for deploying a group of road safety marker assemblies 21 in a predetermined pattern such as wedge and then adjusting the taper of the wedge.

[0081] In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained. When introducing elements of the present invention or the preferred embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0082] As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 

What is claimed is:
 1. A road safety marker assembly comprising: a road safety marker; a drive wheel supporting at least a portion of the road safety marker above a road surface to permit movement of the road safety marker assembly relative to the road surface; and a motor drivingly connected to the drive wheel for driving said drive wheel to self-propel the assembly relative to the road surface.
 2. A road safety marker assembly as set forth in claim 1 comprising at least three wheels arranged relative to each other to support the entire road safety marker above the road surface, the drive wheel constituting one of said at least three wheels.
 3. A road safety marker assembly as set forth in claim 2 wherein the drive wheel is a first drive wheel constituting one of said at least three wheels, the motor being a first motor drivingly connected to the first drive wheel, the road safety marker assembly further comprising a second drive wheel constituting a second one of said at least three wheels, the second drive wheel being spaced from said first drive wheel.
 4. A road safety marker assembly as set forth in claim 3 wherein the second drive wheel is free from any connection with the first motor, the assembly further comprising a second motor drivingly connected to the second drive wheel for driving said second drive wheel independently of the first motor driving the first drive wheel.
 5. A road safety marker assembly as set forth in claim 3 wherein the assembly comprises exactly three wheels, the third one of said three wheels being a caster, the first drive wheel and the second drive wheel being generally coaxial on a common rotation axis, the caster being spaced from the rotation axis of the first and second drive wheels whereby said first and second drive wheels and said caster are spaced from each other to generally define a triangular configuration therebetween.
 6. A road safety marker assembly as set forth in claim 5 wherein the assembly has a weight and a center of gravity, said center of gravity of the assembly being generally within the triangular configuration defined by the first and second drive wheels and the caster.
 7. A road safety marker assembly as set forth in claim 1 further comprising a base adapted for receiving the road safety marker thereon to support said at least a portion of the road safety marker above the road surface, the drive wheel being mounted on the base.
 8. A road safety marker assembly as set forth in claim 7 wherein the road safety marker is free of any fixed connection with the base such that the marker may be removed from the base.
 9. A road safety marker assembly as set forth in claim 8 wherein the road safety marker is free of any releasable connection with the base.
 10. A road safety marker assembly as set forth in claim 9 wherein the road safety marker is generally barrel-shaped and has an open lower end adapted for seating on the base, the base having a positioning member for positioning the lower end of the road safety marker on the base.
 11. A road safety marker assembly as set forth in claim 10 wherein the lower end of the road safety marker is generally circular, said base also being generally circular, the positioning member extending up from the base generally radially inward of the periphery of the base whereby the positioning member and the base together define a generally annular shoulder for positioning the lower end of the road safety marker on the base.
 12. A road safety marker assembly as set forth in claim 1 further comprising a base adapted for receiving the road safety marker thereon to support said at least a portion of the road safety marker above the road surface, the motor being mounted on the base.
 13. A road safety marker assembly as set forth in claim 1 further comprising a base adapted for receiving the road safety marker thereon to support said at least a portion of the road safety marker above the road surface, the base and the road safety marker together defining an enclosure, the motor being disposed in the enclosure.
 14. A road safety marker assembly as set forth in claim 13 wherein the road safety marker is generally barrel-shaped and has a side wall, a closed upper end and an open lower end received by the base for seating the road safety marker on the base, said road safety marker having a generally hollow interior whereby the base, the side wall of the road safety marker and the closed upper end of the road safety marker together define said enclosure.
 15. A road safety marker assembly as set forth in claim 1 further comprising a receiver for receiving a control signal, said motor being electrically connected to the receiver and being responsive to the signal to drive rotation of the drive wheel to move the assembly relative to the road surface.
 16. A road safety marker assembly as set forth in claim 15 wherein the drive wheel is a first drive wheel constituting one of said at least three wheels and the motor is a first motor drivingly connected to the first drive wheel, said assembly further comprising a second drive wheel constituting a second one of said at least three wheels, the second drive wheel being spaced from said first drive wheel and free of driving connection with the first motor, and a second motor drivingly connected to the second drive wheel for driving said second drive wheel independently of the first motor driving the first drive wheel, said second motor being electrically connected to the receiver and responsive to the control signal for driving the second drive wheel.
 17. A road safety marker assembly as set forth in claim 15 wherein the control signal is generated remote from the receiver.
 18. A road safety marker assembly as set forth in claim 17 further comprising a remote pointing device responsive to manual input by an operator and an input circuit for remotely generating the signal in response to the manual input by the operator via the remote pointing device.
 19. A road safety marker assembly as set forth in claim 1 further comprising a control circuit for selectively controlling movement of the road safety marker relative to the road surface, said motor being responsive to the control circuit to move the assembly relative to the road surface.
 20. A road safety marker assembly as set forth in claim 19 wherein the control circuit monitors movement of the assembly relative to the road surface.
 21. A road safety marker assembly as set forth in claim 20 further comprising an encoder associated with the motor for generating an encoded signal representative of a rotary position of the motor, said control circuit receiving and being responsive to the encoder signal for determining the position the assembly.
 22. A road safety marker assembly as set forth in claim 19 further comprising a receiver for receiving a control signal, said motor being electrically connected to the receiver and being responsive to the signal to move the assembly relative to the road surface.
 23. A road safety marker assembly as set forth in claim 22 wherein the control signal is a radio frequency (RF) signal and the receiver is a RF receiver.
 24. A road safety marker assembly as set forth in claim 22 wherein the control circuit is responsive to the control signal received by the receiver for selectively determining movement of the assembly relative to the road surface.
 25. A road safety marker assembly as set forth in claim 19 wherein the movement of the assembly generally comprises a left and right element, a forward and reverse element, a braking element, and a velocity element.
 26. A road safety marker assembly as set forth in claim 19 wherein the control circuit transmits information representative of a current orientation, a current position, and a current velocity of the assembly relative to the road surface.
 27. A road safety marker assembly as set forth in claim 19 further comprising a computer readable medium storing computer executable instructions for controlling the movement of the assembly, said control circuit executing the instructions to control operation of the motor for driving the drive wheel.
 28. A road safety marker assembly as set forth in claim 27 wherein the computer readable medium stores instructions for determining movement of the assembly according to a predetermined path.
 29. A road safety marker assembly comprising: a road safety marker; and a base adapted for receiving the road safety marker thereon and having at least three wheels mounted thereon for moving the assembly relative to the road surface, said at least three wheels being arranged relative to each other such that the base supports the entire road safety marker above the road surface.
 30. A road safety marker assembly as set forth in claim 29 wherein the road safety marker is free of any fixed connection with the base such that the marker may be removed from the base.
 31. A road safety marker assembly as set forth in claim 30 wherein the road safety marker is free of any releasable connection with the base.
 32. A road safety marker assembly as set forth in claim 31 wherein the road safety marker has a lower end adapted for seating on the base, the base having a positioning member for positioning the lower end of the marker on the base.
 33. A road safety marker assembly as set forth in claim 32 wherein the lower end of the road safety marker is generally circular and has a central opening therein, said base also being generally circular, the positioning member extending up from the base generally radially inward of the periphery of the base whereby the positioning member and the base together define a generally annular shoulder for positioning the lower end of the road safety marker on the base with the positioning member received in the central opening of the lower end of the road safety marker.
 34. A road safety marker system comprising: a plurality of road safety marker assemblies, each of said assemblies comprising: a road safety marker; a base supporting the road safety marker, said base having a drive wheel supporting the road safety marker assembly to permit movement of the assembly relative to a road surface; a motor drivingly connected to the drive wheel for driving the wheel to self-propel the road safety marker assembly relative to said road surface; and a control circuit for selectively controlling movement of the road safety marker assembly relative to the road surface, said motor being responsive to the control circuit to move the assembly relative to the road surface.
 35. A road safety marker system as set forth in claim 34 wherein the control circuit of each assembly includes a receiver for receiving a control signal, said motor of each assembly being electrically connected to the respective receiver and being responsive to the signal to move the assembly relative to the road surface.
 36. A road safety marker system as set forth in claim 35 wherein the receiver of each assembly receives the same control signal.
 37. A road safety marker system as set forth in claim 35 wherein the control circuit of one of the assemblies includes a transmitter for transmitting the control signal to the receiver of at leas t one other assembly.
 38. A road safety marker system as set forth in claim 34 wherein the control circuit of at least one of the assemblies includes a computer readable medium storing instructions for determining movement of the respective assembly according to a predetermined path.
 39. A road safety marker system as set forth in claim 38 wherein the control circuit of said at least one of the assemblies includes a computer readable medium storing instructions for determining movement of a plurality of the assemblies according to a predetermined path.
 40. A method of establishing a road construction work zone comprising the steps of: deploying at least one road safety marker assembly on a road surface at a first location remote from a desired location of said at least one road safety marker assembly, said desired location of said at least one road safety marker assembly corresponding to the road safety construction work zone, said road safety marker assembly comprising a road safety marker, a drive wheel supporting at least a portion of the road safety marker above the road surface to permit movement of the road safety marker assembly relative to the road surface, and a motor drivingly connected to the drive wheel for driving said drive wheel to self-propel the assembly relative to the road surface; and instructing said at least one road safety marker assembly to move under its own power to said desired location of said at least one road safety marker assembly remote from said first location of said at least one road safety marker assembly.
 41. A method as set forth in claim 40 wherein the road safety marker assembly further comprises a receiver for receiving a control signal, said motor being electrically connected to the receiver and being responsive to the signal to drive said drive wheel to self-propel the assembly relative to the road surface, said step of instructing said at least one road safety marker assembly comprising transmitting a signal to the receiver of said at least one road safety marker assembly from a location remote from said at least one road safety marker assembly. 